The Spaniards face the Portuguese side in Lisbon in the Round of 16 first leg tie, and will face either Lille or Borussia Dortmund in the quarter-finals.
Advertisement
Advertisement
However, he claims his side must be at their best to qualify as the 38-time Primeira Liga winners are not pushovers.
"I think in this phase there's no easy game, every team deserves to be here at this stage, and I think Benfica too," Flick told the media.
"Benfica is a fantastic team, tomorrow we play in a great stadium and it's really a special atmosphere there.
"Their (fans) push the team on a lot, supporting them and it will be really tough tomorrow, hard work for us."